分子筛吸水速度研究

分子筛在高压电气产品中具有吸附气室水分和气室内电弧分解物的作用,对保持气室内气态平衡起到至关重要的作用。以分子筛为样本,以其饱和吸水率为基础,在相同条件下计算不同时间其达到饱和吸水率的百分比,拟合出吸水速率曲线,对高压产品装配具有指导作用。

沥青混合料试件吸水饱和度对水稳定性影响

改变不同空隙率试件浸水时间及温度后测定试件吸水饱和度,研究了浸水时间、水温及空隙率对吸水饱和度的影响规律。结果表明,浸水时间对试件吸水饱和度有显著影响;水温对吸水饱和度有较大影响,相同空隙率试件吸水饱和度随着温度的升高而增加;提出了浸水饱和残留稳定度作为水稳定性判断指标。现行试验规程规定采用统一浸水时间的试验条件值得商榷,建议根据实际情况调整浸水时间以保证试件达到浸水饱和状态。

基于水下钢球法的混凝土抗冲磨试验研究

对有刚玉环氧复合砂浆材料涂层的混凝土试件进行干、湿状态下的抗冲磨试验,针对水工混凝土试验规程所列试验方法中存在的不足,优化了试验方法。结果表明:试件在充分浸水饱和与绝对干燥的状态下的磨失量具有较好的一致性,采用绝对干燥状态下材料的磨失量来评价材料的相对抗冲磨性更为科学、准确。

过量浸水对基质块N、P、K流失及秧苗生长的影响

[目的]研究过量浸水对基质块N、P、K流失及秧苗生长的影响。[方法]设计让基质块吸水饱和膨胀后再多加其体积1/2的过量水,并设13个时间梯度用来研究一次性过量浸水与基质块N、P、K养分浸出、损失的回归关系,并种植西红柿研究基质块泡水后对植株养分吸收及生长的影响。[结果]3种养分在浸泡水中的浓度与时间都存在回归方程分别为:N=-2E-05t2+0.016 1t+2.055 3、P=0.002 2t+2.248 5及K=0.004 7t+0.875 8。虽然3种养分都有损失,但氮损失总量与时间的回归方程方差分析差异不显著,这与其挥发性质有关,而P、K的回归方程为:P=0.125 7t-0.117、K=0.022 5t0.1514。这样造成植株地上部对N、K的吸收产生不利影响,回归方程分别为:N=20.64e-4E-04t、K=E-06t2-0.011 3t+29.055。同时,在该试验条件下,过量浸水未对壮苗指数造成显著不利影响。[结论]为指导基质块浸水方式及其栽培管理和育苗提供理论依据,同时指导农业生产。

空隙特征对砂岩水致劣化规律的影响

针对南京秦淮东河开挖后的稳定性问题,选取黄马青组(T_(2h))砂岩为研究对象,对砂岩在吸水-干燥循环条件下的单轴抗压、抗拉特性进行试验研究。考虑到未来边坡运营过程中水的影响,试验时分别考虑自然吸水和饱和吸水两种情况。根据试验结果对所研究砂岩的空隙特征、水致劣化特征和劣化机制进行了详细分析。随着吸水-干燥循环次数增加,岩石的抗压、抗拉强度和凝聚力均呈劣化趋势,说明循环次数的增加对岩石的损伤有累积作用。岩石自然吸水条件下(小开空隙未进水时)强度和弹性模量下降速度较慢,而饱和吸水条件下(开空隙被水充满时)强度和弹性模量下降速度较快,表明岩石中小开空隙对岩石的劣化效果显著。微观结构分析结果表明,随着吸水-干燥循环次数增加,岩石中空隙率增大。结合抗剪强度特征分析认为,干-湿循环导致岩石的黏结强度不断下降,而摩擦强度变化较小,表明黏结强度劣化是岩石水致劣化的主要原因,干-湿循环导致水-岩反应,岩石颗粒胶结物发生松散,边缘发生开裂,宏观上表现为岩石劣化。该研究成果对于新开挖河道边坡稳定性分析具有较大的参考价值,为河岸边坡的长期稳定性分析提供了依据。

Impacts of Excessive Soaking on N, P, and K in Substrates Plots and Seedling Growth

[Objective] The aim was to study on impacts of excessive soaking N, P, and K insubstrate plots of and seedling growth. [Method] Substrate was designed to add additional 1/2 water after saturation and expansion. Disposable excessive soak- ing and regression relation of nutrition infusion of substrate plots were studied by design of 13 time gradient. Plant nutrition absorption and growth effects after sub- strate plots immersed by water were investigated by growing tomato. [Result] Con- centration and time of the three nutrition immersed in water had the regression equation of each, as follows： N=-2E-05t2＋0.016 lt＋2.0553, P=0.002 2t＋2.248 5 and K=0.004 7t＋0.875 8. With nutrition loss of the three, however, loss amount was al- most same with variance analysis of regression equation, which may result from its volatilization. Regression equations of P and K were： P=0.125 7t-0.117, and K=0.022 5t.1514, which led to adverse impact on plant absorption of N and K above ground, whose equations were N=20.64e-4E-0.4t, and K=E-06t2-0.011 3t＋29.055. Meanwhile, un- der the condition, sound seedling index was not impacted a lot by excessive immer- sion. [Conclusion] This study has provided theoretical reference for guidance of sub- strate plot soaking method, cultivation and regulation, and breeding, as well as agri- cultural production.

The Unsaturated Hydraulic Parameters for Aeolian Sand

The water characteristic curve for aeolian sand in two processes of wetting and drying was obtained by the negative water column technique.The values of fitting parameters were calculated according to Van Genuchten formula and the parameters that characterized the prosperities of aeolian sand such as the unsaturated infiltration coefficient and specific water capacity were obtained.The results showed that the water characteristic curve for aeolian sand in wetting process had greater hysteresis quality than ...

蒸压加气混凝土抗冻性能研究

通过与抗冻性有关的基本原理介绍,说明蒸压加气混凝土孔结构的特殊性和低吸水饱和度奠定了其良好抗冻性的基础,而合理的原料配合比和蒸压养护制度,提高托勃莫来石的结晶度,以改善孔结构和提高孔间壁的强度,是其良好抗冻性能的保证,对此介绍相关的试验研究和应用实践作为佐证。而在建筑应用过程中强调,应重视蒸压加气混凝土表面孔隙特征,做好易受潮部位的防水处理,以提高建筑物的耐久性。

不同状态再生细骨料对混凝土性能的影响研究

研究干燥状态再生细骨料与饱和吸水状态再生细骨料掺量对混凝土性能的影响。结果表明:采用100%干燥状态与饱和吸水状态再生细骨料,1 h坍落度损失分别为160 mm、100 mm,再生细骨料吸水饱和后,可改善混凝土工作性;再生细骨料状态对混凝土抗压强度的影响规律相同,干燥状态与饱和吸水状态再生骨料混凝土28 d抗压强度分别提高了3.5%、4.7%;一元线性回归方程及方差分析表明,再生细骨料掺量对再生骨料混凝土28 d抗压强度的影响是显著的。

Adsorption of Pb^(2+) on macroporous weak acid adsorbent resin from aqueous solutions: Batch and column studies

The adsorption properties of a novel macroporous weak acid resin （D152） for Pb^2＋ were investigated with chemical methods. The optimal adsorption condition of D152 resin for Pb^2＋ is at pH 6.00 in HAc-NaAc medium. The statically saturated adsorption capacity is 527 mg/g at 298 K. Pb^2＋ adsorbed on D152 resin can be eluted with 0.05 mol/L HCI quantitatively. The adsorption rate constants determined under various temperatures are k288 n=2.22×10-5 s^-1, k298 K=2.51 × 10^-5 s^-1, and k308 K= 2.95 × 10^-5 s^-1, respectively. The apparent activation energy, Ea is 10.5 kJ/mol, and the adsorption parameters of thermodynamics are ΔH^Θ=13.3 kJ/mol, ΔS^Θ=119 J/（mol·K）, and ΔG^Θ298 K =-22.2 kJ/mol, respectively. The adsorption behavior of D152 resin for Pb^2＋ follows Langmuir model.

Condensation of Water Vapor on Waterproof Breathable Fabrics

Condensation occurs when the local vapor pressure rises above the saturation vapor pressure at the local temperature in theory. A new measuring apparatus were made to obtain temperature and relative humidity simultaneously for the purpose of investigating the mechanism of condensation occurred on the fabrics. The experiment conducted at the standard condition of temperature of 20℃ and relative humidity of 65%. The result obtained from experiment showed that condensation could occur under the situation closed to saturation line as the temperature on fabric may be lower than dew point of water vapor in the measuring box depending on the experiment conducted at an ambient environment temperature of 20℃ The range of fabrics studied showed that PTFE laminated fabrics except nylon gingham PTFE laminated fabric facilitates the loss of water vapor and therefore prevent condensation. It is necessary to develop studies from a wide range of fabrics, especially breathable fabrics and under bad experiment condition in order to develop fabrics, which could eliminate condensation, or transport water vapor through the fabric while remaining waterproof.

不同固含量PAN浆液制备的抗起球腈纶的性能研究

采用固含量分别为9%,13%的聚丙烯腈(PAN)浆液,通过湿法转向纺丝工艺制备常规腈纶及抗起球腈纶,研究了两种不同固含量PAN浆液的流变性能,以及PAN浆液固含量对抗起球腈纶截面形貌、饱和吸水倍率、力学性能的影响。结果表明:在相同温度下,固含量为9%的PAN浆液的表观黏度更低,高频区的弹性效应更小;相较于固含量为13%的PAN浆液制备的1.67 dtex抗起球腈纶,以固含量为9%的PAN浆液制备的0.89 dtex抗起球腈纶内部结构更松散,微孔更多,且饱和吸水倍率提高了约39%,力学性能明显下降,结强结伸乘积为18.92,经马丁代尔法测试抗起球级数达到4级。

An improved Mesri creep model for unsaturated weak intercalated soils

The weak intercalated soils in redbed soft rocks of Badong formation have obvious creep characters. In order to predict the unsaturated creep behaviors of weak intercalated soils, an unsaturated creep model was established based on the unsaturated creep tests of weak intercalated soils by using GDS triaxial apparatus. The results show that the creep behaviors of intercalated soils are apparent and significantly affected by matric suction. Based on this, an empirical Mesri creep model for intercalated soils under varying matric suctions was built. The fitting results show that the parameters Ed and m of this model are in good power relations with matric suction s and stress level Dr, respectively. An improved Mesri creep model was established involving stress-matric suction-strain-time, which is more precise than the Mesri creep model in predicting the unsaturated creep behaviors of weak intercalated soils.

利用核磁共振测定木材润胀细胞壁的水分含量与孔径分布

【目的】利用核磁共振冻融分析技术测定杉木与杨木两种速生材细胞壁润胀状态吸着水含量与孔隙分布情况,为改性剂粒径选择与改性效果评价提供方法。【方法】常温下获得试样内水分T_2弛豫信号总量,通过核磁冻融分析系统对试样进行降温处理,检测不同冷冻温度条件试样内未冻结水分信号量;依据Gibbs-Thomson效应确定凝固点降低与孔径的关系,并以此分析孔径分布。【结果】核磁冻融法测定杉木和杨木吸着水饱和含量约为38%,高于通过吸湿外推法估算数值,与溶剂排出法、多孔板法、离心法结果相近;核磁冻融分析法避免了常温条件按照T_2弛豫分布确定吸着水含量偏小的现象;两种速生材试样细胞壁润胀状态孔径小于1.59 nm的孔隙占比约为75%,大于4.56 nm的孔隙占比不超过6%,与溶剂排出法、光谱标记法结果相符。【结论】核磁共振冻融分析技术可较为便捷准确地获得木材吸着水含量与细胞壁孔隙分布,其结果可用于指导改性剂粒径的选择与改性效果评价。